PREFERRED STOCK. Our Certificate of Incorporation authorizes the issuance of 20,000,000 shares of preferred stock, par value $0.10 per share. There are no shares of preferred stock outstanding. The preferred stock may be issued by resolution of our Board of Directors at any time without any action of the stockholders. The Board of Directors may issue the preferred stock in one or more series and fix the designation and relative powers. These include voting powers, preferences, rights, qualifications, limitations, and restrictions of each series. The issuance of any such series may have an adverse effect on the rights of holders of common stock and may impede the completion of a merger, tender offer, or other takeover attempt.

COMMON STOCK. Our Certificate of Incorporation authorizes 480,000,000 shares of common stock, par value $0.10 per share. Subject to the rights of preferred stock, which may from time to time be outstanding, holders of common stock are entitled to receive dividends out of funds legally available, when and if declared by the Board of Directors, and to receive their share of the net assets of the company legally available for distribution upon liquidation or dissolution.

For each share of common stock held, stockholders are entitled to one vote on each matter to be voted on by the stockholders, including the election of directors. Holders of common stock are not entitled to cumulative voting. The stockholders do not have preemptive rights. All outstanding shares of common stock are fully paid and nonassessable.

STOCK AWARD PLANS. Stock-based compensation cost is measured at the grant date based on the value of the award and is recognized as expense as it vests. A summary expense recognized within personnel expenses in our consolidated statements of operations and comprehensive income for stock-based compensation is as follows (in thousands):


	2021		2020		2019
Stock options	$	16,128	$	20,162	$	16,073
Stock awards	110,701		20,985		20,170
Company expense on ESPP discount	3,148		2,848		2,840
Total stock-based compensation expense	$	129,977	$	43,995	$	39,083

On May 9, 2019, our shareholders approved an amendment and restatement of our 2013 Equity Incentive Plan (the “Plan”) to increase the number of shares authorized for award by 4,000,000 shares. The Plan allows us to grant certain stock awards, including stock options at fair market value and performance shares and restricted stock units, to our key employees and outside directors. At the time our shareholders approved adding additional shares to the plan, a maximum of 17,041,803 shares are available to be granted under this plan. Approximately 1,780,727 shares were available for stock awards under this plan as of December 31, 2021. Shares subject to awards that expire or are canceled without delivery of shares or that are settled in cash, generally become available again for issuance under the plan.

STOCK OPTIONS. We have awarded stock options to certain key employees that vest primarily based on their continued employment. The value of these awards is established by the market price on the date of the grant, discounted for post-vesting holding restrictions, calculated using the Black-Scholes option pricing model and is being expensed over the vesting period of the award. Although participants can exercise options via a stock swap exercise, we do not issue reloads (restoration options) on the grants.

The following schedule summarizes stock option activity in the plans. All outstanding unvested options as of December 31, 2021, relate to time-based grants from 2015 through 2020.


	Options	Weighted Average Exercise Price		Aggregate Intrinsic Value (in thousands)		Average Remaining Life (years)
Outstanding at December 31, 2020	7,260,840	$	76.37	$	127,065	6.6

Exercised	(748,198)	71.95
Forfeitures	(18,778)	76.03
Outstanding at December 31, 2021	6,493,864	$	76.88	$	199,682	5.8

Vested at December 31, 2021	4,789,677	$	76.08			5.2
Exercisable at December 31, 2021	4,789,677	$	76.08			5.2

As of December 31, 2021, unrecognized compensation expense related to stock options was $26.6 million. The amount of future expense to be recognized will be based on the passage of time and the employees' continued employment.

Additional potential dilutive stock options totaling 3,924 for 2021 have been excluded from our diluted net income per share calculations because these securities’ exercise prices were anti-dilutive (e.g., greater than the average market price of our common stock).

The following table summarizes these unvested stock option grants as of December 31, 2021:


First Vesting Date	Last Vesting Date	Options Granted, Net of Forfeitures	Weighted Average Grant Date Fair Value(1)		Unvested Options
December 31, 2018	December 31, 2022	1,441,636	$	14.25	276,353
December 31, 2019	December 31, 2023	1,154,019	20.12		451,674
December 31, 2020	December 31, 2024	1,638,791	13.87		976,160
		4,234,446	$	15.70	1,704,187

We estimated the fair value of stock options granted using the Black-Scholes option pricing model. We estimate the fair value of restricted shares and units using the Black-Scholes option pricing model-protective put method. A description of significant assumptions used to determine the risk-free interest rate, dividend yield, expected volatility, and expected term are as follows:

Risk-Free Interest Rate-The risk-free interest rate was based on the implied yield available on U.S. Treasury zero-coupon issues at the date of grant with a term equal to the expected term.

Expected Term-Expected term represents the period that our stock-based awards are expected to be outstanding and was determined based on historical experience and anticipated future exercise patterns, giving consideration to the contractual terms of unexercised stock-based awards.


	2020 Grants		2019 Grants
Weighted-average risk-free interest rate	1.6%		2.1%
Expected dividend yield	2.5%		2.0%
Weighted-average volatility	23%		25%
Expected term (in years)	8.91		6.08
Weighted average fair value per option	$	13.88	$	17.52

STOCK AWARDS. We have awarded performance-based restricted shares, performance-based restricted stock units, and time-based restricted stock units. All of our awards contain restrictions on the awardees’ ability to sell or transfer vested awards for a specified period of time. The fair value of these awards is established based on the market price on the date of grant, discounted for post-vesting holding restrictions. The discounts on outstanding grants vary from 12 percent to 24 percent and are calculated using the Black-Scholes option pricing model-protective put method. The duration of the restriction period to sell or transfer vested awards, changes in the measured stock price volatility and changes in interest rates are the primary reasons for changes in the discount. These grants are being expensed based on the terms of the awards.

We have awarded performance-based restricted shares through 2020 to certain key employees and non-employee directors. These awards vest over a five-year period based on the company’s earnings growth. In 2021, we have awarded performance-based restricted stock units to certain key employees and non-employee directors. These awards vest over a three-year period based on the company's cumulative three-year earnings per share growth and annual adjusted gross profit growth. These performance-based restricted stock unit awards contain an upside opportunity of 200 percent contingent upon obtaining certain earnings per share and adjusted gross profit targets.


	Number of Restricted Shares and Restricted Stock Units	Weighted Average Grant Date Fair Value
Unvested at December 31, 2020	1,102,211	$	67.29
Granted(1)	292,993	74.92
Performance-based grant adjustment(2)	29,147	67.13
Vested	(980,188)	67.37
Forfeitures	(36,521)	71.10
Unvested at December 31, 2021	407,642	$	72.21


First Vesting Date	Last Vesting Date	Performance Shares and Stock Units Granted, Net of Forfeitures	Weighted Average Grant Date Fair Value (1)		Unvested Performance Shares and Restricted Stock Units

December 31, 2019	December 31, 2023	354,005	$	73.79	70,756
December 31, 2020	December 31, 2024	401,548	59.34		80,268
December 31, 2021	December 31, 2025	285,765	74.91		256,618
		1,041,318	$	68.53	407,642

We granted an additional 330,072 performance-based restricted stock units at target on February 9, 2022. These awards have a weighted average grant date fair value of $76.74 and will vest over a three-year period based upon our cumulative three-year earnings per share growth and annual adjusted gross profit growth.

We award time-based restricted stock units to certain key employees and non-employee directors. Time-based awards granted through 2020 vest over a five-year while time-based awards granted in 2021 vest over a three-year period primarily based on the passage of time and the employee's continued employment.

The following table summarizes our unvested time-based restricted share and restricted stock unit grants as of December 31, 2021:


	Number of Restricted Shares and Stock Units	Weighted Average Grant Date Fair Value
Unvested at December 31, 2020	598,039	$	60.24
Granted	666,311	72.09
Vested	(439,695)	69.29
Forfeitures	(61,174)	68.12
Unvested at December 31, 2021	763,481	$	69.42

We granted an additional 634,118 time-based restricted stock units on February 9, 2022. These awards have a weighted average grant date fair value of $74.67 and will vest over a three-year period with a first vesting date of December 31, 2022.

As of December 31, 2021, there was unrecognized compensation expense of $88.3 million related to previously granted stock awards. The amount of future expense to be recognized will be based on the company’s earnings growth and the continued employment of certain key employees.

EMPLOYEE STOCK PURCHASE PLAN. Our 1997 Employee Stock Purchase Plan allows our employees to contribute up to $10,000 of their annual cash compensation to purchase company stock. Purchase price is determined using the closing price on the last day of the quarter discounted by 15 percent. Shares are vested immediately. The following is a summary of the employee stock purchase plan activity (dollar amounts in thousands):


	Shares Purchased By Employees	Aggregate Cost to Employees		Expense Recognized By the Company
2021	220,970	$	17,838	$	3,148
2020	236,062	16,146		2,848
2019	224,596	16,093		2,840

SHARE REPURCHASE PROGRAMS. In May 2018, the Board of Directors authorized a share repurchase program that allows the Company to repurchase 15,000,000 shares of our common stock. On December 9, 2021, the Board of Directors increased the company’s share repurchase authorization by an additional 20,000,000 shares of common stock. As of December 31, 2021, we have 21,635,388 shares remaining under the share repurchase authorization. The activity under these authorizations is as follows (dollar amounts in thousands):


	Shares Repurchased	Total Value of Shares Repurchased
2019 Repurchases	3,434,102	$	306,444
2020 Repurchases	2,542,915	182,745
2021 Repurchases	6,154,364	580,818